Alas madness has set in; a very specific kind of madness, not uncommon on the AVS forums: rear projection optical path optimisation. First, I thought why not have a ratio of 2.4:1 instead of 16:9, not just for films, but also for PC gaming. Ok, some more throw length required to cover the width so two mirrors instead of one, in fact the more the better so let's extend beyond the deepest viable wall position with some concrete pipe segments (waterproofing be damned);

Ah, but the brightest non-professional 4K projector you can get is only 2000 lumens and that is only a brightness of 20 nits. But what about using a 1.5 optical gain screen? Well, incidence angle must be below 13 degrees to achieve an acceptable center to corner screen brightness ratio. This requires an optical path length of 9.5m. At this point I realised that technically, no could stop me from just excavating a huge trench under the experiment chamber.

9.5m is coincidentally the maximum throw distance for the Sony VPL-VW1100ES in 16:9 mode, so that works out nicely. Obviously this would also be useful as somewhere to put the pulse forming network when it comes to installing the teleporter.

The wife is expressing some skepticism about the need for five separate projectors (and that's just 2D content). But then, she still hasn't seen Wargames yet. I'm sure a film evening can convince her of the necessity of a Big Board in every War Room.

This has taken a hideously long time mostly due to the astounding, yet wholly unsurprising, inefficiency of local government beurecracy. However structural design is finally complete: the engineer deleted all the steels except the hoist beams, repalcing them with integrated R/C, and switched all the steel mesh to individual rods.

The 3D view really makes it clear that the overall size is bigger than the main house, and indeed, the average detached house here. Because of course MAD SCIENCE is more important than mere living accomodations. The next step is temporary piling; I am collecting quotes now.

Construction of the upper pile wall was prioritised due to the fact that the 1950s mortared stone retaining wall bellow the house had buckled, and was risking subsidence of the house. Spec is 14 x 450mm piles with R/C capping beam, 5 x 25mm rebar cages in each. Drilling was delayed for days by mysterious and inexplicable faults in the piling rig. Finally, as the last bore of the first pass reached 11 metres below ground (this type of pile wall is done in two passes), a screeching and wailing noise errupted from the hole. The crew were visibly concerned but pushed on. At 12 metres the drill string snapped, leaving 4 metres of auger stuck in the hole. The crew worked through Saturday to force backfill into the shaft, recover the buried drill components and then re-bore the hole ready for concrete pouring.

This type of auger is extremely sturdy and the strata is relatively soft chalk; cause of the failure remains undetermined.

Ugh. Screeching and wailing is steel on steel in my experience. Once welded the tip of a core drill to some rebar by trying to push past it.

Could have been an unusually large flint inclusion. Could have been an old waste tip . Purely in a detached professional capacity, because I don't know where you are in relation to London and its old airfields, was the risk of UXOs ever discussed?

madd0ct0r wrote:Could have been an unusually large flint inclusion. Could have been an old waste tip . Purely in a detached professional capacity, because I don't know where you are in relation to London and its old airfields, was the risk of UXOs ever discussed?

The site is 1.5km from RAF Kenley, which was one of the three main fighter airfields defending London in the second world war. All UXO was thoroughly cleared postwar though.

Internet connectivity has been down for four months now, excepting 4G wireless which has a tragically low (20GB) cap. Progress was slowed by the groundwork contractor walking off the job (apparently ceased trading). I'm now organising labour and plant myself on day rates / weekly hire.

We are about to pour concrete for the optical trench. I changed the outer formwork for the lower walls from temporary aluminium system to 140mm concrete blockwork (left in place), to act as retaining walls to appease building control inspectors and to avoid the sheer hassle of renting the stuff, setting it up and worst of all getting it back out again. Also adds some strength to the walls and avoids having to use angle iron to support the upper brickwork form wall.

The sump floor and walls were done with on-site mixed concrete; the full cube form is waiting to be buried under the floor slab. Crazed beurecrats at the council demanded a radon/methane proof gas membrane on top of the DPC membrane even though the former is also completely waterproof. I took the opportunity to sandwich an additional conductive foil layer inbetween for enhanced screening. That will now be two dedicated foil layers, one encapsulated layer and two insulation bonded layers on the floor slab. I've also changed the inner formwork for all the walls and roof slabs to galvanised corrugated steel roofing sheets (also left in place, with lots of through bolts for concrete bonding). It's actually cheaper than using plywood or hiring/setting up/removing temporary aluminium formwork and (when thoroughly multi-point grounded) is an effective EM screen, plus it provides backup waterproofing. Of course it will require substantial temporary bracing.

The structural engineer specified 5m ish rebar lengths with lots of overlaps and ties but I don't see the point. I intend to use full span single pieces of rebar (8 to 12m) for the suspended slabs. We'll need a mobile crane to get the bundles from an articulated HGV on the road to the staging area, but I'll probably make up the cost on the reduced labour and it will be stronger. For the lower slab the sheer stress is negligible (¬200m of solid chalk down to the sandstone bedrock, it's not going to shift significantly) so I'm using heavily lapped fabric mesh with extra bar around the corners and edges.

So far I've done all the onsite carpentry and a bit of general labouring shifting spoil around and sealing/cleaning things up. To date specifically for this job I've acquired an impact driver, a petrol concrete vibrator, a heavy duty hammer drill (my standard mains drill died), two 3m scaffold towers (mainly to support my half-tonne power winch), 25 1-tonne traffic barriers (plus assorted pedestrian barriers), a 16mm electro-hydralic 'portable' rebar bender (which weighs 30kg and looks like a power armour close combat weapon), an automatic rebar tying gun and 50 used 2 tonne props (I already had a variety of angle grinders). Largely because the cost of hiring most of this stuff is about three weeks == new purchase price, 2 weeks == second hand purchase price, so might as well just buy it.

Check with the structural engineer about changes. Sometimes changes don't seem like they could be an issue, until your suspended walkway falls down because someone changed the design. I suspect that the single length may be more prone to breaking under tension. Or it may just be for easy construction.

"preemptive killing of cops might not be such a bad idea from a personal saftey[sic] standpoint..." --Keevan Colton
"There's a word for bias you can't see: Yours." -- William Saletan

I did and naturally he was trying to bill me for a complete redesign for trivial things like the rear wall width being 350mm instead of 200mm (I prefer to define 'mitigrate crack propagation risk' as 'stuff a few sheets of mild steel fabric mesh in there'). The lapped rebar thing was definitely ease of construction though, he incorrectly assumed that I wouldn't be crazy enough to crane 5 tonnes of steel directly over my neighbour's house from a HGV parked on the road. Meanwhile all the contractors and buildings control think the design is thoroughly overengineered as it is. Hopefully the floor slab will be poured this week.

My latest dubious idea is to replace the stairwell with a wheelchair ramp. This will require cantilevering some pop-out underground alcoves, but it will definitely simplify the Dr Strangelove reenactments.

Damn, I saw the plans and read the numbers, but seeing the big damn hole you've dug makes it look a hell of a lot more impressive.

Also, cute kid.

Baltar: "I don't want to miss a moment of the last Battlestar's destruction!"
Centurion: "Sir, I really think you should look at the other Battlestar."
Baltar: "What are you babbling about other...it's impossible!"
Centurion: "No. It is a Battlestar."

Corrax Entry 7:17: So you walk eternally through the shadow realms, standing against evil where all others falter. May your thirst for retribution never quench, may the blood on your sword never dry, and may we never need you again.

This reminds me of why everyone but North Korea stopped building forts.

"This cult of special forces is as sensible as to form a Royal Corps of Tree Climbers and say that no soldier who does not wear its green hat with a bunch of oak leaves stuck in it should be expected to climb a tree"
— Field Marshal William Slim 1956

This reminds me of why everyone but North Korea stopped building forts.

Today, on "Destroyed in seconds"....

But seriously, that's quite an impressive project. A few minor modifications, and it might double as a nuclear fallout shelter, if not as a bunker...

A minute's thought suggests that the very idea of this is stupid. A more detailed examination raises the possibility that it might be an answer to the question "how could the Germans win the war after the US gets involved?" - Captain Seafort, in a thread proposing a 1942 'D-Day' in Quiberon Bay

I apologise for the disgusting dead organic material temporarily cluttering up the construction zone. One concrete is in place all of it will be stripped out, skipped, and probably recycled into toothpicks and/or American stick homes.

Formwork in high-stress areas e.g. door frames, corners, roof beams is formed of 8mm thick equal-angle structural sections which will be left in place to add strength to the structure. I've also doubled the cross sectional area of the rebar in the beams and some areas of the floor slab.

Getting concrete into the upper part of the lower walls required construction of the slab formwork first; the concrete pipeline is extremely heavy and even with five guys on site it's impractical to heft around. The intermediate slab weight will be approx 35 tonnes; the formwork is supported on about 70 Acrow props.

The galvanised steel sheet is working well; correctly braced, it's more rigid than plywood, weatherproof and cheaper. Also blocks mobile phone signals to reduce interruptions to the construction crew. The five main beams are 400mm x 300mm, 5 x 16mm rebar primary reinforcing, 12mm secondary reinforcing, with the lower section cased by four sections of 6mm steel angle for extra strength (and convenience when building them). Lots of of 2x8, 2x6 and 2x4 used in the temporary bracing.

Side drainage recently went in; there are seven 175mm drains on each side of the building: front threshold, roof downpipe, side path, and four air intake chambers. Earthing system also went in just before the concrete pour: 12 x 1.2m solid copper earth rods embeded at depths between 2 and 4 metres around the perimeter walls.

Looks like I'll have to buy the first bit of A/V gear early: my 10-year old Onkyo receiver just lost the ability to output HDMI. So now we can have sound or video in the living room but not both. I'm looking at the Denon AVR X6400, which is 11.2 for maximum speaker count silliness. It can go in the living room for now and move to the Test Chamber later. Alas, still no wired internet, keep hitting the transfer cap on the 4G and having to buy top-ups.

Slow progress on this build over the winter/spring but things have picked up recently.

Lower chamber after the walls were completed

Interim lighting solution

Wheelchair access under construction

Elite construction crew pondering their next move

Pouring the intermediate slab : 53 tonnes of waterproof concrete. The concrete I'm using has nearly six times the compressive strength of standard concrete blocks (tensile strength is provided by the rebar).

After this pour the biological material could be removed from the lower chamber; all of it went back into bracing up the ramp area.

The main door is 5m wide with 2.3m headroom

Fire escape hatch; the main risk is vehicles catching fire in the upper chamber, as there is no wood and minimal plastic used in the building.

The roof over part of the ramp forms a workbench, 3.4m wide x 1.2m deep x 0.9m worktop height (concrete to be poured tomorrow).

There is a greyhound-sized sink and area for washing machine and dryer built into the concrete structure. These minature concrete walls and slabs use galvanised weld-mesh for reinforcement.

The door into solid chalk is not only to confuse building inspectors, it will allow for an underground connection to the main house to be added later.

I told my wife that this apperture is for a future utility duct but it's actually the lower entrance to a Jefferies tube & escape tunnel.

Baltar: "I don't want to miss a moment of the last Battlestar's destruction!"
Centurion: "Sir, I really think you should look at the other Battlestar."
Baltar: "What are you babbling about other...it's impossible!"
Centurion: "No. It is a Battlestar."

Corrax Entry 7:17: So you walk eternally through the shadow realms, standing against evil where all others falter. May your thirst for retribution never quench, may the blood on your sword never dry, and may we never need you again.

A minute's thought suggests that the very idea of this is stupid. A more detailed examination raises the possibility that it might be an answer to the question "how could the Germans win the war after the US gets involved?" - Captain Seafort, in a thread proposing a 1942 'D-Day' in Quiberon Bay